• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3
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• pp.388-393
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• 2013

Carbon fiber reinforced plastic (CFRP) has many desirable qualities, including being lightweight and very strong. These characteristics have led to its use in applications ranging from small consumer products to vehicles. Circular and square CFRP members were fabricated using 8ply unidirectional prepreg sheets stacked at different angles ($[+15^{\circ}/-15^{\circ}]_4$, $[+45^{\circ}/-45^{\circ}]_4$ and $[90]_8$, where $0^{\circ}$ coincides with the axis of the member). Based on the collapse characteristics of a CFRP circular member, the collapse characteristics and energy absorption capability were analyzed. Impact collapse tests were carried out for each section member. In this study, the impact energies at crossheads speeds of 5.52 m/s, 5.14 m/s and 4.57 m/s were 611.52 J, 529.2 J and 419.44 J (circular member) 2.16 m/s, 1.85 m/s and 1.67 m/s are 372.4 J, 274.4 J and 223.44 J (square member). The purpose is to experimentally examine the absorption behavior and evaluation the strength in relation to changes in the stacking configuration when the CFRP circular members with different stacking configurations were exposed to various impact velocities. In addition, the dynamic characteristics were considered.

• Steel and Composite Structures
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• v.23 no.3
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• pp.273-283
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• 2017

In this paper, it is aimed to present a detail investigation related to structural behavior of laterally unrestrained steel cantilever roof of tribune with slender cross section. The structure is located in Tutak town in $A{\breve{g}}r{{\i}}$ and collapsed on October 25, 2015 at eastern part of Turkey is considered as a case study. This mild sloped roof structure was built from a variable I beam, and supported on steel columns of 5.5 m height covering totally $240m^2$ closed area in plan. The roof of tribune collapsed completely without any indication during first snowfall after construction at midnight a winter day, fortunately before the opening hours. The meteorological records and observations of local persons are combined together to estimate the intensity of snow load in the region and it is compared with the code specified values. Also, the wide/thickness and height/thickness ratios for flange and web are evaluated according to the design codes. Three dimensional finite element model of the existing steel tribune roof is generated considering project drawings and site investigations using commercially available software ANSYS. The displacements, principal stresses and strains along to the cantilever length and column height are given as contour diagrams and graph format. In addition to site investigation, the numerical and analytical works conducted in this study indicate that the unequivocal reasons of the collapse are overloading action of snow load intensity, some mistakes made in the design of steel cantilever beams, insufficient strength and rigidity of the main structural elements, and construction workmanship errors.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.89-94
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• 2004

A steel plated is typically composed of plate panels. The overall failure of the structure is certainly affected and can be governed by the bulking and plastic collapse of these individual members. In the ultimate limit state design, therefore, a primary task is to accurately calculate the buckling and plastic collapse strength of such structural members. Structural elements making up steel palated structures do not work separately, resulting in high degree of redundancy and complexity in contrast to those of steel framed structures. To enable the behavior of such structures to be analyzed, simplifications or idealizations must essentially be made considering the accuracy need and degree of complexity of the analysis to be used. Generally the more complex the analysis the greater is the accuracy that may be obtained. The aim of this study is the investigation of the effect of the tripping behaviour including section characteristic for a plate under uniaxial compression. For this purpose of study, in used elasto-plasticity deformation FEA method are used for this study.

• Structural Engineering and Mechanics
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• v.83 no.3
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• pp.401-413
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• 2022

The collapse of civil infrastructure due to natural disasters results in financial losses and many casualties. In particular, the recent increase in earthquake activities has highlighted on the importance of assessing the seismic performance and predicting the seismic risk of a structure. However, the nonlinear behavior of a structure and the uncertainty in ground motion complicate the accurate seismic response prediction of a structure. Artificial intelligence can overcome these limitations to reasonably predict the nonlinear behavior of structures. In this study, a deep learning-based algorithm was developed to estimate the time-history seismic response of bridge structures. The proposed deep neural network was trained using structural and ground motion parameters. The performance of the seismic response prediction algorithm showed the similar phase and magnitude to those of the time-history analysis in a single-degree-of-freedom system that exhibits nonlinear behavior as a main structural element. Then, the proposed algorithm was expanded to predict the seismic response and fragility prediction of a bridge system. The proposed deep neural network reasonably predicted the nonlinear seismic behavior of piers and bearings for approximately 93% and 87% of the test dataset, respectively. The results of the study also demonstrated that the proposed algorithm can be utilized to assess the seismic fragility of bridge components and system.

• Earthquakes and Structures
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• v.23 no.6
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• pp.527-534
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• 2022

EDCC (Eco-Friendly Ductile Cementitious Composites) is a recently created class of engineered cementitious composites that exhibit extremely high ductility and elastoplastic behavior under pure tension. EDCC contains reduced amounts of cement and very large volumes of fly ash. Due to these properties, EDCC has become one of the solutions to use in seismic upgrading. This paper discloses previous studies and research that discussed the seismic upgrading of unreinforced, non-grouted, unconfined, and non-load bearing masonry walls which are called URM infill walls using the EDCC technique. URM infill wall is one of the weak links in the building structure to withstand the earthquake waves, as the brittle behavior of the URM infill walls behaves poorly during seismic events. The purpose of this study is to fill a knowledge gap about the theoretical and experimental ways to use the EDCC in URM infill walls. The findings reflect the ability of the EDCC to change the behavior from brittle to ductile to a certain percentage behavior, increasing the overall drift before collapse as it increases the energy dissipation, and resists significant shaking under extensive levels with various types and intensities.

• Structural Engineering and Mechanics
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• v.45 no.3
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• pp.311-321
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• 2013

In this study, to have a better judgment on the structural performance, the effects of dynamic Soil-Structure Interaction (SSI) on seismic behaviour and lateral structural response of mid-rise moment resisting building frames are studied using Finite Difference Method. Three types of mid-rise structures, including 5, 10, and 15 storey buildings are selected in conjunction with three soil types with the shear wave velocities less than 600m/s, representing soil classes $C_e$, $D_e$ and $E_e$, according to Australian Standard AS 1170.4. The above mentioned frames have been analysed under two different boundary conditions: (i) fixed-base (no soil-structure interaction), and (ii) flexible-base (considering soil-structure interaction). The results of the analyses in terms of structural lateral displacements and drifts for the above mentioned boundary conditions have been compared and discussed. It is concluded that the dynamic soil-structure interaction plays a considerable role in seismic behaviour of mid-rise building frames including substantial increase in the lateral deflections and inter-storey drifts and changing the performance level of the structures from life safe to near collapse or total collapse. Thus, considering soil-structure interaction effects in the seismic design of mid-rise moment resisting building frames, particularly when resting on soft soil deposit, is essential.

• International Journal of High-Rise Buildings
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• v.4 no.1
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• pp.65-73
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• 2015

Detailed finite element (FE) analyses of a full-scale four-story steel frame structure, subjected to consecutive 60% and 100% excitations from the JR Takatori records during the 1995 Hyogoken-Nanbu earthquake, are conducted using E-Simulator. The four-story frame was tested at the largest shake-table facility in the world, E-Defense, in 2007. E-Simulator is a parallel FE analysis software package developed to accurately simulate structural behavior up to collapse by using a fine mesh of solid elements. To reduce computational time in consecutive dynamic time history analyses, static analysis with gravity force is introduced to terminate the vibration of the structure during the analysis of 60% excitation. An overall sway mechanism when subjected to 60% excitation and a story mechanism resulting from local buckling of the first-story columns when subjected to 100% excitation are simulated by using E-Simulator. The story drift response to the consecutive 60% and 100% excitations is slightly smaller than that for the single 100% excitation.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.2_2
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• pp.245-254
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• 2020

This study investigated the so far little-researched characteristics of the behaviors of rock slopes at the time of an earthquake. For the selection of the rock block, a proper model was formed by applying the similarity in consideration of the roughness and strength of the rock slope(10m) on the site, and shaking table tests were carried out according to seismic excitement acceleration, and seismic waves. In the case of the inclination angle of the joint plane of 20°, the long period wave at 0.3g or more at the time of the seismic excitement surpassed the length of 100mm, the permissible displacement (0.01H, H:slope height), which brought about the collapse of the rock; the short period wave surpassed the permissible displacement at 0.1g, which caused the collapse of the slope. The rock slope was close to a rigid block and a structure more vulnerable to the long period wave than to the short period wave. It collapsed in the short period wave even at the seismic amplitude smaller than the maximum design acceleration in Korea.

• Journal of the Korean Society of Safety
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• v.29 no.5
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• pp.67-73
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• 2014

Construction equipment such as tower crane should be installed in a field without appropriate anchorage to cause a collapse of crane. The anchorage capacity can be varied with Anchor length, concrete strength, anchor diameter, hooked or non hooked these variables will be made and tested in the study. It is shown what anchorage capacity will be more effective case by case. Hooked and non-hooked rebar anchor concrete weight with dia 22mm rebar are shown with initial displacement at 170~220KN of hooked case and 200~210KN of non-hooked one which are linearly increased, without any ductility behavior with almost brittleness. Three(3) same test pieces are almost similarly behaviored without relation to hooked or non-hooked cases. It is found out that the bigger diameter of rebar becomes, the more resistant capacity could be made, but conversely ductility against sudden collapse similar to brittleness becomes the more insufficient. It is also found out that dia 16mm rebar could be more effectively applied to heavy support weight at construction sites.

• Journal of Astronomy and Space Sciences
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• v.16 no.2
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• pp.105-114
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• 1999

Archival long-slit spectra, covering the wavelength range 4050~5150$\AA$, have been used to investigate the radial behavior of absorption line features (G4300, Fe4383, Ca4455, Fe44531, Fe4668, and H$\beta$) of an eliptical galaxy NGC 5322. The heliocentric recession velocity of NGC 5322 has been derived as 1888$\pm$51kms-1. Metallic absorption lines of NGC 5322 show significant radial gradients through the major axis. The minor axis shows much smaller radial metal line gradients than the major axis. The minor axis shows much smaller radial metal line gradients than the major axis. The mean slopes of Fe line gradients to the major and minor axes of NGC 5322 were estimated as -0.433$\pm$0.064 and -0.242$\pm$0.096, respectively. Significant radial gradients of H$\beta$ absorption of NGC 5322 are also detected both on the major and minor axes. It is shown that the radial metallicity gradients in NGC 5322 are smaller than expected in a simple dissipative collapse model. Rather, dissipationless collapse, such as hierarchical merhing, could have contributed during the initial stage of the galaxy formation.